Login without e-mail

As regulations regarding student privacy are always increasing I would like to suggest an alternative to e-mail login for students. If a teachers buy an account with a certain amount of logins, for example 20. He could then create a world and invite 20 students on the same wireless network using a code, like there is now. This would be possible if the app had a button "login without e-mail" or "join a world without login". This would bypass many privacy issues, particularly in Europe where the regulations are very strict. Alternatively teachers could buy logins, for example 20 logins (usernames and passwords) that would not require an email.